There is growing interest in using renewable feedstocks for manufacturing biofuels, such as bioethanol, biochemicals, and animal feed. Such products can be produced from lignocellulosic biomass (“biomass”) using chemical and biochemical processes, such as acid catalysis, enzymatic catalysis, fermentation and animal digestion. However, lignocellulosic fibers in the biomass comprise a complex network of structural carbohydrates (i.e., polysaccharides) containing cellulose, hemicellulose and lignin, which are difficult to extract. As such, pretreatment of the biomass is needed to increase the rate and/or yield at which monosaccharide moieties and/or soluble sugar oligomers within the structural carbohydrates are subsequently obtained.
However, pretreatment attempts to date have fallen short of the desired economic and technical performance. For example, certain types of pretreatments degrade some of the sugars, thus reducing yields and inhibiting subsequent biological conversion of the remaining sugars. Additionally, when chemicals are used in pretreatment, they can be difficult to recover at a reasonable cost. Residual chemicals can also negatively affect downstream conversion operations. The effectiveness of many pretreatments is limited, such that the ultimate conversions of structural carbohydrates obtained, independent of lost yield by sugar degradation reactions, is inadequate for competitive process economics.
Inexpensive polysaccharides from renewable plant biomass can become the basis of chemical and fuels industries, replacing or substituting petroleum and other fossil-fuel feedstocks. Highly reactive lignocellulosic biomass can also become the basis of improved animal feeds, particularly for ruminant animals. However, effective, economical pretreatments are needed to make these polysaccharides available at a sufficiently high yield and acceptable cost.